Appearances can be deceiving. The light from a light bulb seems steady, but it flickers 120 times per second. Because the brain perceives only an average of the information it receives, this flicker is blurred and the perception of constant illumination is a pure illusion.
Although light cannot escape from a black hole, the strong glow of fast-circulating gas has its own unique flicker. In a recent newspaper, published in Astrophysical journal letters, Lena Murchikova, William D. Loughlin Member of the Institute of Advanced Studies; Chris White of Princeton University; and Sean Ressler of the University of California Santa Barbara could use this subtle flicker to construct most things exact model so far of our own galaxy’s central black holes—Sagittarius A * (Sgr A *) – provides insight into properties such as its structure and movement.
For the first time, researchers in a single model have shown the whole story of how gas travels in the middle of the Milky Way – from being blown by stars to falling into the black hole. By reading between the infamous lines (or flickering lights), the team concluded that the most likely image of black hole feeding in galactic center involves direct incident gas from large distances, rather than a slow suction of orbiting material over a long period of time.
“Black holes are the doormen of their own secrets,” Murchikova stated. “To better understand these mysterious objects, we depend on direct observation and high-resolution modeling. “
Although the presence of black holes was predicted about 100 years ago by Karl Schwarzschild, based on Albert Einstein’s new theory of gravity, scientists are only now beginning to investigate them through observations.
In October 2021, Murchikova published an article in Astrophysical journal letters, introduces a method for studying black hole flicker on a time scale of a few seconds, instead of a few minutes. This progress enabled a more accurate quantification of Sgr A *’s properties based on its flicker.
White has worked with the details of what happens to the gas near black holes (where the strong effects of general relativity are important) and how this affects the light that comes to us. One Astrophysical journal The publication earlier this year summarizes some of his findings.
Ressler has spent years trying to construct the most realistic simulations to date of the gas around Sgr A *. He has done this by incorporating observations of nearby stars directly into the simulations and carefully tracing the material they throw out when it falls into the black hole. His latest work culminated in one Astrophysical journal letters newspaper 2020.
Murchikova, White and Ressler then came together to compare the observed flicker pattern for Sgr A * with those predicted by their respective numerical models.
“The result turned out to be very interesting,” Murchikova explained. “We thought for a long time that we could largely ignore where the gas around the black hole came from. Typical models imagine an artificial ring of gas, roughly monk-shaped, at some great distance from the black hole. We found that such models produce patterns. of flicker not in accordance with observations. “
Ressler’s stellar wind model takes a more realistic approach, where the gas consumed by black holes is originally emitted by stars near the galactic center. When this gas falls into the black hole, it reproduces the correct pattern of flicker. “The model was not built with the intention of explaining this particular phenomenon. Success was in no way a guarantee,” Ressler commented. “So, it was very encouraging to see the model succeed so dramatically after years of work.”
“When we study flicker, we can see changes in the amount of light emitted by the black hole second by second, making thousands of measurements in a single night,” White explained. “However, this does not tell us how the gas is arranged in space as a large-scale image would do. By combining these two types of observations, it is possible to mitigate the limitations of each and thereby obtain the most authentic image.”
Lena Murchikova et al, Remarkable correspondence between Sagittarius A * submillimeter variability with a stellar wind-fed Accretion Flow Model, The Astrophysical Journal Letters (2022). DOI: 10.3847 / 2041-8213 / ac75c3
Lena Murchikova et al, Second-scale Submillimeter Variability of Sagittarius A * under Flaring Activity of 2019: On the Origin of Bright Near-infrared Flares, The Astrophysical Journal Letters (2021). DOI: 10.3847 / 2041-8213 / ac2308
Christopher J. White et al, The Effects of Tilt on the Time Variability of Millimeter and Infrared Emission from Sagittarius A *, The Astrophysical Journal (2022). DOI: 10.3847 / 1538-4357 / ac423c
Sean M. Ressler et al, Ab Initio Horizontal scale simulations of magnetically arrested accretion in Sagittarius A * Powered by stellar winds, The Astrophysical Journal (2020). DOI: 10.3847 / 2041-8213 / ab9532
Institute for Advanced Studies
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